At
the major league level, teams tell us what they expect from position
regulars based on how much playing time they allot to players. That's
why we don't present strict league averages by position with this
feature. Instead an attempt is made to define position regulars by
singling out the most tenured players at each position.

First,
we went to Baseball-Reference's wonderful Play Index database. Those
players with at least 750 plate appearances (600 PA for catchers) in a
two-year span who spend the majority of their time at one position are
considered regulars. Left and right field count as one position, corner
outfield.

The periods sampled were: 2000-01, when teams averaged
5.01 runs per nine innings; 2005-06, which featured 4.78 R/9; and
2010-11, with its average of 4.37 R/9.

Applying the criteria
outlined above tended to exclude those players who were too green or too
unproductive or too injury-prone to rack up consistent playing time
over the duration of two seasons. It also removed placeholders and
injury fill-ins from the sample, while allowing for some disabled-list
time by injured regulars.

Also, by setting a high PA threshold,
we allow more time for player performance to stabilize. This means that
particularly good or bad seasons tend to get evened out, and rookies
have time to build steam and hit at a more representative rate.

Using
these parameters, we were able to account for between 80 and 90 percent
of major league regulars at any one time. The two exceptions being
first base and second base in today's game, where teams seem to be in a
state of transition as they introduce young regulars.

For
example, teams turned over first base last season to youngsters such as
Eric Hosmer (Royals), Freddie Freeman (Braves), Paul Goldschmidt
(Diamondbacks), Mark Trumbo (Angels) and Mitch Moreland (Rangers).
Others like Yonder Alonso (Padres) and Brandon Belt (Giants) and Anthony
Rizzo (Cubs) stand on deck for this season.

With regulars identified
around the diamond, we can define average production based on median
values at each position. So from each position sample we identify the
median value for batting average (which is closely associated with a
player's hit tool) and the median value for home runs (hitting for power
tool) and then fan out in both directions, using the median as a
midpoint.

Think of a player with a median home run total this
way: Half the regulars at his position will have more home runs, and
half will have fewer. See our position-by-position graphics for a practical application of median values and also to find out which players best exemplify the concept of average for their positions.